Variation of Juglans nigra in central Texas and south-central Oklahoma should be studied; specimens seemingly intermediate between J . nigra and both J . major and J . microcarpa have been seen from this area. E. C. Twisselman (1967) incorrectly reported that J . nigra was locally naturalized in California; his specimens were all J . hindsii (possibly introgressed with J . nigra ) and J . californica .

Juglans nigra is frequently cultivated as an ornamental, and the nuts are prized for their strong, distinctive flavor.